Sinn Fein's policing spokesperson Gerry Kelly, a member of the Stormont assembly, said a version of the document with the officers' names removed, was posted on a wall facing the party's office on the Falls Road in Belfast overnight.

A photo of Mr Kelly and a threatening message - saying "Gerry, we know who your mates are" - were posted alongside the document.

The PSNI previously revealed that dissident republicans claimed to be in possession of the document, which would amount to a severe security issue for the force.

The document, which had mistakenly been shared online, included the names of around 10,000 officers and staff.

"This is a very obvious attempt by dissident republicans to intimidate me," Mr Kelly said.

"Even more sinister, this is a very public indication that the dissidents do have access to the sensitive information in the data leak document. It therefore represents a very real threat to the officers, and the civilian staff involved."

Mr Kelly said he believed it was the "main intention" of the incident to verify the claim that they have access to leaked documents.

"I have of course reported this incident to the PSNI and I would appeal to anyone with information to bring that information forward.

"Sinn Fein represents the vast majority of people in the nationalist community and we will certainly not be intimidated by dissident groups who have virtually no support and who offer nothing but disruption and threats in an attempt to make themselves relevant.

"They should disband and end their anti-community activities."

Speaking later, Mr Kelly said the redacted version contained details of a "substantial number" of officers.

"One of the staff in the office got in touch with me this morning when he came into work. He noticed that on the side of the library there was a number of documents pasted up," he said.

"There was a photograph of myself and then there was a statement saying in large writing 'Gerry, we know who your mates are'.

"Under that there was what appeared to be, and what turned out to be, a section of the leaked documents that were put out.

"It did not have the names of the police officers involved, but it had everything else. It wasn't the whole 10,000 (names), but it was a substantial number."

The PSNI said they were investigating the incident.

Assistant chief constable Chris Todd said: "From the outset we have been planning for this potential development and that plan is now being put into place.

"We recognise the impact this may have on our officers, staff and their families and additional security and reassurance patrols have already been implemented across Northern Ireland as part of our organisational response.

"The safety and welfare of our officers and staff remains our priority and we have reminded them of their personal safety and security both on and off duty."

The data breach occurred when the PSNI responded to a Freedom of Information request seeking the number of officers and staff of all ranks and grades across the organisation.

In the response to this request, a table was embedded which included the surname, initial, location and departments for all PSNI employees as well as rank and grade data.

It also revealed members of the organised crime unit, intelligence officers stationed at ports and airports, officers in the surveillance unit and almost 40 PSNI staff based at MI5's headquarters in Holywood.

The table was potentially visible to the public for between two-and-a-half to three hours last week.

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A representative body for officers said they have been left "shocked, dismayed and basically angry" by the breach.

Police in Northern Ireland are under threat from terrorists, with the current assessed level of threat at severe, meaning an attack is highly likely.

Senior detective John Caldwell was seriously injured when he was shot by gunmen at a sports complex in Co Tyrone in February.

Chief constable of the PSNI Simon Byrne said earlier this year that he receives briefings almost every day about plots to attack and kill his officers, adding that the ongoing threat from dissident republicans remains a "real worry".